Cosette Ellison was 15 when her body was found in a ravine at the foothills of Mount Diablo in Contra Costa County, California, on January 1, 1971. She had been missing since late 1970; her remains were discovered nude and partially buried. Investigators have noted disturbing similarities between Cosette’s case and other unsolved Contra Costa County murders from that period, especially the deaths of Maureen Field and Lisa Ann Beery, and the dump site closely matched locations used for other victims.

Authorities have suspected a possible link to Philip Joseph Hughes, a convicted serial killer tied to other murders in the area, and there has been speculation about a connection to the Zodiac Killer, but no definitive link has been established. The killing remains unsolved. Does anyone have information about Cosette, her last known whereabouts, or the foothills area where she was found?